const fp = require('lodash/fp')


const cars = [
    {name: 'Ferrari FF', horsepower: 660, dollar_value: 700000, in_stock: true},
    {name: 'Spyker C12 Zagato', horsepower: 650, dollar_value: 648000, in_stock: false},
    {name: 'Jaguar XKR-S', horsepower: 550, dollar_value: 132000, in_stock: false},
    {name: 'Audi R8', horsepower: 525, dollar_value: 114200, in_stock: false},
    {name: 'Aston Martin One-77', horsepower: 750, dollar_value: 1850000, in_stock: true},
    {name: 'Pagani Huayra', horsepower: 700, dollar_value: 1300000, in_stock: false},
]

/**
 * 练习1
 */
let isLastInStock = fp.flowRight(fp.prop('in_stock'), fp.last)
// console.log(isLastInStock(cars))

/**
 * 练习2
 */

let firstCarName = fp.flowRight(fp.prop('name'), fp.first)
// console.log(firstCarName(cars))

/**
 * 练习3
 */
let _average = function (xs) {
    return fp.reduce(fp.add, 0, xs) / xs.length
}

let averageDollarValue = fp.flowRight(_average, fp.map(fp.prop('dollar_value')))
// console.log(averageDollarValue(cars))

/**
 * 练习4
 */
let _underscore = fp.replace(/\W+/g, '_')

let sanitizeNames = fp.map(fp.flowRight(_underscore, fp.lowerCase))
console.log(sanitizeNames(['Hello world']))